Dynamical Modeling of the Stellar Nucleus of M 31
نویسنده
چکیده
We present stellar dynamical models of the lopsided, double–peaked nucleus of M31, derived from Hubble Space Telescope (HST) photometry. A Schwarzschild–type method, in conjunction with Richardson–Lucy deconvolution, was employed to construct steadily rotating, hot, stellar disks. The stars orbit a massive dark object, on prograde and retrograde quasi–periodic loop orbits. Our results support Tremaine’s eccentric disk model, extended to include a more massive disk, non zero pattern speed (Ω), and different viewing angle. Most of the disk mass populated prograde orbits, with ≃ 3.4% on retrograde orbits. The best fits to photometric and kinematic maps were disks with Ω ≃ 16 km s pc . We speculate on the origins of the lopsidedness, invoking recent work on the linear overstability of nearly Keplerian disks, that possess even a small amount of a counter– rotating component. Accretion of material—no more massive than a globular cluster—onto a preexisting stellar disk, will account for the mass in our retrograde orbits, and could have stimulated the lopsidedness seen in the
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تاریخ انتشار 2001